Catalytic composition



Patented Sept. 14, 1943 CATALYTIC COMPOSITION Grafton R. Owens, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a

corporation of Delaware No Drawing. Application July 13, 1939, Serial No. 284,201

6 Claims. (01. 260-498) The present invention relates to a new composition of matter which is particularly adapted as an aid in effecting catalytic reactions. More particularly, the present invention relates to a new mercury catalyst containing boric acid as an activating or promoting substance.

Illustrative of one of the uses of the new catalytic composition is the employment thereof in ester formation involving reacting acetylene and relatively active organic acids, such for example as formic acid, chloracetic acid and their equivalents.

In the past it has been proposed to prepare vinyl esters by reacting acetylene and certain organic acids in the presence of a mercury compound having a catalytic action. In such processes, however, the reaction between acetylene and the carboxylic acid takes place very slowly. Moreover, the catalyst soon loses its efiiciency.

There have been in consequence many attempts made to improve this method of preparing vinyl esters by adding to the reaction mixture another substance or substances tending to promote the reaction and increase the lifetime of the mercury catalyst. Thus, so-called stron acids as sulfuric and ortho phosphoric acids have been so employed. The use of both these catalysts tends to form by-products and discoloration of the ester. Furthermore, sulfuric acid and ortho phosphoric acid are extremely poor activators or promoters for the reaction between acetylene and formic acid. They dehydrate formic acid producing carbon monoxide and water. Consequently, it is impractical to employ strong mineral acids as activator or promoters for the reaction between acetylene and formic acid. It could not then have been foreseen that a mercury catalyst in conjunction with a boric acid activator or promoter would possess such desirable improved catalytic properties that it will catalyze the reaction between even formic acid and acetylene, which reaction proceed o poorly when catalyzed by either of the mercurysulfuric acid or mercury-ortho phosphoric acid catalysts.

It has also been proposed in British Patent 459,882 to I. G. Farbenindustrie Aktiengesellschaft to react acetylene and certain aliphatic acids in the presence of a mercuric oxide-boric oxide and hydrofluoric acid composition or mercuric oxide-boric acid and hydrofluoric acid composition. Such a catalytic mixture doubtless results in the formation of boron trifluoride disclosed in United States Patent Number 1,912,608 to Walter Weibezahn dated June 6, 1933. The

present invention as is readily apparent i in no way related to these processes. Furthermore, the use of hydrofluoric acid is accompanied by many disadvantages. It is exceptionally corrosive and 'this alone offers many operating difliculties.

An object of this invention is then to provide a new relatively cheap organic catalyst.

Another object of this invention is to provide a catalyst which is especially adaptable for the promotion of ester formation.

Another object of this invention is to provide a method for the formation of vinyl esters.

A further object of this invention is to provide a method for the formation of vinyl esters of strong aliphatic acids, such for example as formic and chloracetic acids.

Other and further objects of the invention will be hereinafter shown.

The following specific examples are understood to be embodiments of the invention showing specific uses of the new catalytic composition of the invention and in no sense limitative of the scope thereof, the parts being by weight.

To parts of anhydrous formic acid placed in a suitable vessel equipped with cooling and agitating means, there is preferably added 0.2 to 0.4 part of mercuric acetate and 0.10 to 0.20 part of boric acid. Into this mixture so obtained, acetylene gas is added rapidly with agitation, maintaining the temperature at substantially 10-20 C. The absorption of the acetylene and reaction with formic acid takes place rapidly. After substantially 38.8 parts of acetylene are added, requiring about one hour, the addition of acetylene is discontinued. In the process of the present invention it is found that the acetylene may be added as rapidly as cooling the solution will permit. Furthermore, it is found that on carrying out the process of the present invention little or no secondary reaction forming ethylidene diformate takes place. On the contrary th reaction product so formed consists substantially entirely of mono-vinyl formate. In many processes heretofore employed for the preparation of vinyl esters, for example vinyl acetate by reacting acetylene with acetic acid in the presence of a mercury catalyst and a promoting substance, the reaction proceeds slowly and the vinyl ester so formed must be removed by means of excess acetylene in order to avoid further reaction, with the accompanying formation of ethylidene diacetate.

On completion of the reaction sufficient sodium formate is added to deactivate the catalyst, and the monovlnyl formate recovered in high yield,

preferably by flash distillation, and separated monovinyl formate. Excellent results were obfrom any unreacted'formic acid. Other convene tained. lent methods of isolating the monovinyl formate In the catalyst composition of the invention, of may, if desirable, b employed. Thus, distillation course, other ratios of the components may be under reduced pressure may be employed, if so 5 employed than those specifically shown. Again desired. Yields of nearly theoretical based on other mercury catalysts than mercuric acetate the acetylene absorbed are obtained employing may be employed with a boric acid activator, as the new catalyst in the manner indicated. will be well-known to those skilled in the art to If desirable, temperatures differing from the which the invention pertains. As-an exampl I preferred temperature of -20 C. may be em- 10 may use mercuric oxide.

ployed for the reaction between acetylene and The present invention is limited solely by the formic acid. Thus, I have employed temperafollowing claims appended hereto as a part of tures as high as 40 C. for this reaction. When this specification.

employing such higher temperatures, however. What is claimed is:

the reaction mixture was somewhat darker than 1. A process of preparing a vinyl ester of a where lower temperatures were employed and lower fatty acid, which comprises reacting acetythere was a slight lowering of the absorption of lene with said organic acid in the presence of a acetylene, catalytic mercury compound and boric acid as Furthermore, if desirable, the quantity of meran activating substance.

cury catalyst and boric acid promoter may be 2. A process of preparing a vinyl ester of a increased over that given above. readily active lower aliphatic acid which com- The esteriflcation process above disclosed may prises reacting acetylene with said aliphatic acid be carried out in the form of a continuous proc in the presence of a catalytic mercury compound ess. Thus, the reaction mixture is withdrawn and boric acid as an activating substance. from the reaction chamber at the desired opti- 3. A process for preparing a vinyl ester of a mum point of reaction, the catalyst deactivated lower fatty acid of the class of formic and chloand the monovinyl formate separated therefrom racetic acids which comprises reacting acetylene by flash distillation or other means. The formic with said aliphatic acid in the presence of a acid in the still residue is recovered by hydrolysis, catalyst consisting in a catalytic mercury comconcentrated and together with the higher boilpound and boric acid. ing fractions of the distillate, comprising unre- 4. A process of preparing vinyl formate comacted formic acid, returned to the system. Fresh prising reacting acetylene with formic acid in the formic acid and catalyst are additionally added presence of a catalyst consisting in a catalytic to complete the charge and the process continued mercury compound and boric acid.

by the addition of acetylene. When operating in 5. A process of preparing vinyl formate comthis manner, preferably the full quantity of boric prising reacting acetylene with formic acid, said acid is employed, but considerably less of the reactants being in contact with mercuric acetate mercury "catalyst may be used since the recovered activated with boric acid.

formic acid is more reactive towards acetylene. 6. A process of preparing mono vinyl formate This highly reactive recovered formic acid causes comprising passing acetylene into formic acid in a marked reduction in the induction period. the presence of a catalyst consisting in a cata- Thus, when employing only 0.2 part by weight of lytic mercury compound and boric acid, deactimercuric acetate, the induction period for the revating said catalyst, recovering the mono vinyl action between acetylene and formic acid is reformate and any unreacted formic acid returning due d to zero. the recovered formic acid to the reaction cham- As another specific example showing the use of ber, adding additional formic acid and said catathe preferred new catalyst, chloracetic acids has lyst thereto and continuing the reaction of acetybeen reacted with acetylene to produce the vinyl lene therewith. ester of chloracetic acid in a manner analogous GRAFTON R. OWENS. to that employed above for the manufacture of 

